The present invention relates generally to the delivery of multimedia content. In particular, the invention relates to the control and delivery of video over an IP-based network.
As high speed digital connections become more common, applications and services are increasingly being offered over such connections. For example, an increasing number of people are transferring their telephony services to broadband-based technologies, such as Voice over IP (VoIP), which provide for the initiating and routing of voice conversations over the Internet or another IP-based network. An increasing number of people are also receiving video such as “cable” television over a broadband connection. One technology for delivering digital television service is Internet Protocol Television (IPTV), which delivers high-quality multi-channel television and streaming video content using an Internet Protocol over an IP-based network, instead of using traditional broadcast or cable technologies. The IPTV content can be played not only on a personal computer or laptop, but can be displayed on a television, cell phone, portable media player, PDA, etc.
Today IPTV typically is delivered using a protocol such as the Real Time Streaming Protocol (RTSP) as well as other such protocols. None of these approaches are based on the session initiation protocol (SIP) or a protocol that separates session control and/or signaling from transport. This lead to problems as, for example, SIP-based devices cannot take full advantage of IPTV and other types of control mechanisms for multimedia data with, for example, VCR-like functionality. As a result it also is difficult to allow a SIP or HTTP/SIP application, for example, to provide IPTV-like services, at best simply serving content catalogs and not much more. Similarly, networks such as IMS designed for SIP cannot directly use IPTV as part of the SIP/IP IMS architecture. The exchange has to be treated as purely network-based, which defeats some of the design principles of IMS. Also, RTSP is a stateful protocol that does not utilize a session ID, such that a permanent TCP connection is not needed, but instead utilizes RTSP messages sent between the client and server. For multicasting video content, a protocol such as the Internet Group Management Protocol (IGMP) is typically used for a linear IPTV service delivery, wherein each host and application desiring to be part of a multicast group must use IGMP to indicate such desire. Adjacent routers must also use this protocol to communicate. Other protocol specifications may be used by some (e.g. for mobile broadcasting), but they all suffer similar issues.
These protocols tend to be complex, and require specific architectures. For companies such as telecommunications companies, which are already losing revenue to cable companies who are now offering telephony services, it would be desirable to be able to offer ITPV using existing telecommunications technologies and architectures, without the need for extensive upgrades and more complex systems. Further, there are services that are not offered by protocols such as RTSP, such as third party control of a stream between a client and a server, that it would be desirable to be able to offer to a customer or third party vendor.